The most extensively studied implementation of an optical reservoir computer is a configuration that uses a single physical node with a time-delayed feedback signal [1]}, as explained in Sec. REF . The input signal is converted into a staircase waveform by a sample-and-hold procedure. A weight mask related to the number of virtual nodes in the feedback loop is applied to each symbol step. The weights of the output signal are calculated offline during the training procedure. In this section we describe this class of systems as well as related designs.
